1. Technical Field
The present invention relates to the field of digital video recording, and more particularly to personal video recorder trick modes.
2. Description of the Related Art
Personal video recorders (PVRs) allow users to view a broadcast multimedia presentation on a delayed schedule, and even permit delayed viewing while the broadcast continues. After recording the broadcast multimedia presentation onto a storage medium is commenced, a user can begin playback of the recorded portion of the multimedia presentation. If a user chooses, he can pause the multimedia presentation while the remainder of the multimedia presentation continues to be recorded. Later the user can recommence playback of the multimedia presentation from where it was paused, or from anywhere else within the recorded portion of the presentation. Further, the user also can perform other trick modes on the recorded material, such as fast forward, rewind, slow motion, fast motion, etc.
Although currently available personal video recorders provide added convenience to users by enabling them to perform trick modes on broadcast presentations, the live presentation of the PVR is delayed. Personal video recorders buffer the video signal derived from a broadcast source via an MPEG encoder, a data storage device, and then through an MPEG decoder before a video signal is provided to a display device. The buffering step results in an appreciable time delay between the actual, real time broadcast occurrence and the resulting display presentation. This time delay is especially inconvenient during a channel change. When a channel is changed the user does not receive display verification of change until the source signal from the new channel has been processed through the buffering step. In some instances this process can take multiple seconds. Further, the time delay during channel changes can be non-uniform. For example, in a cable television system that provides both analog channels and digital channels, typically a PVR can have a non-uniform buffer delay because analog video source signals require encoding, for example using MPEG compression, prior to storage, whereas no such delay results with broadcast digital video signals which are MPEG compressed prior to transmission. Hence, changing channels in a system incorporating a PVR can be an inconvenient and frustrating experience. Furthermore rapid channel hopping or surfing is largely precluded by the delay in new channel content display.